Telephone-exchange system



Dec. 16, 1930. G. H. MORENCY TELEPHONE EXCHANGE SYSTEM Filed June 10, 1929 MARG/NAL INVENTUR G. H. MORE/VG) v oneness r1. rzroaeneY, or POBTLAND,.; OREGON,.ASSIGNOR TOQAMERICANJ TELEPHGNE Patented Dec. 16, 193i) TST es Parser Fri-4e arm 'rntneaarrrconrenr, A CORPORATION or new YonK rE ErHoivE-eXonArren SYSTEM Application filed June 10,

This invention relates to telephone systems, and more particularly to automatic systems in which line-switches are employed.

The object of this invention isto improve thequality of telephone service by reducing the frequency with which double connections occur in systems of the character above mentioned. y I

According to one feature of this invention,

a'margi'nal relay is inserted in a lead which connects battery to theplungermagnets of each switch in a group' o'f secondary linee,

switches. The arrangement is'such that-ifthe circuit branch through more than one plunger magnet is "established'at any given instant the common 'marginal relay will operate and open the lead which connects to battery. The marginal relay is quick-aching while the plungermagnets are sluggish,

so that under the conditions assumed the marginalzrelay prevents the plunger magnets trom operating. 1 Y r p Accordmg to another feature ot the nvention, the operation of a marginal relay, which is inserted in the lead which connects battery tothe plunger magnets of each switch ina group of secondary switches, not-only prevents the simultaneous plunging of two or more secondary line-switches, but also prevents the immediate recurrence of such a com dition after the release of the primary lineswitches by causing a redistribution of all idle primary line-switches with respect to the secondary line-switchesh The drawing illustrates a portion of an automatic telephone system in which this in-- vention hr s been embodied. Referring to the dravin A represents diagrammatically a callin bscribers stat on, B represents a called snbscribers station, D represents a primary line-switchQE a primary master switch, F and G represent secondary lineswitches. H represents a secondary masterswitch, 5% represents a selector switch and C represents a connector switch.

The calling subscribers station A is'shown connected over the line 1 tothe springs 4 and of the primary line-switch through which the line may be connected to the trunk 31. The line-switch D, which is individual 1929. Serial No. 369157;;

to the line 1,is oneot a group ofprimary lineswitches, all of which are associated with the primary master-swltchE. The primary line-switch D is of the well known -Keith type and may be similar to that des'cribed on pages 47, 48 and 49 o'fthesecond edition of Automatic Telephony by Smith and Campbell. The master-switch E is'similarjto that v illustrated in Figure-16 on page 48 and descrlbedonpages 49 and 50" but modified for use when both primary and secondary 'line- Y switches are furnished, as illustrated in Fig die 78 on page 85and as'described'on pages 87 and 88 of the second'edition of Smith and CampbelL The trunk- 3-l", which is multipled over leads'll to other primary line-switches in the groupwith switch D, is one of a group oftrunks to which all of these primary line;

switches have access. The line 1 is multipl-led over leads 10 to other springs (similar to springs 4i and 5) through which the line 1" may be connected to the other trunks in the same group withtrunk 3-1. The line 1 is also multipledover leads 80 to the banks of con? nector switches through which calls are'completed when thestation A is the called station The trunks to which'the primary lineswltches have access terminate at, and are each connected to, secondary line-switches such as F andG. The trunk 31 is shown connect-ed to springs 34 and 35, of the secondary switch'F, through which a-connection may] beextended to trunk 63. The switch F, which is individualto the trunk 31, is one of a group of secondary line switches, all of which are, associated with the secondary master-switch H. The second'ary switch Gis one of the switches-in this group. The'trunk63, which 7 switch G, represent one of a group of trunks (similar to springs 34 and of the switch F, through which the trunk 31 may be connected to. the other trunks in the group with trunk 63. The trunking scheme between the which are accessible to the line-switches in a primary group other than the onewith which the master-switch E is associated. ,This

trunk, which is shown connected to springs 44 and of the secondary switch G, is aul-a tipled over heads to other springs, of switch G, through which it' may be connectedto. any

other of the trunks in the same group with trunk 63.

The trunks, to

lines; each trunkis individualto the selector 63 isshown connected to a selectorswitch S,

which is diagrammatically; represented by the brushes andthe. broken lines connecting thereto. 7 The selector S has access, under control of a calling deviceat the calling sta -a tion, to trunks one of which is' shown as terminating at the connectorgswitch G. The" connector C, which is diagrammaticallyfi'epresented by the brushes 1.67 and the broken lines connecting thereto, has access, under control of the calling device at .thecalling;

station, to. s ubscribers. lines, oneot which,

i line 68,.isshown as terminatingat the called ill and. Campbell. 1

station Bf :The selector switch S is of the type illustrated in Figure 62,011 page 62 and Figure 63 on page 63 and describedon pages 62 to- 65, inclusive of the second edition ofv AutomaticTelephony? by Smith. and Camp-V bell. The connector switch C isot the type illustrated in, Figure 60,01'1 page; 59 and described on pages 57 to 61, inclusive, of Smith The operation of a system inwhichthis invention is embodied, as shown in the drawing, will now. be described in detail; primary and secondary master, switches E andH are'not shown in theirentirety, the parts shown being limited to those which are involved in the disclosure of the invention.

Assume that the shaft .1 1 of the master-" switch E is in such a position that the lineswitchplungers, suchas 9, which are engaged by said shaft. are :opposite the springs of trunk 31. l/Vhen the receiver is removed from the receiver hook at station A to originate a call, an obvious circuit is closed over line l toioperate the line relay 2. Inoperating, re lay 2 closes a circuit from battery through the :backcontact of relay 23, over the openwhich the secondary line, switches have access, terminate at, andareconnected to, selector switches used further extending connections from, calling main? battery lead 12, and through the lefthand (pull-down) winding of line-switch magnet 8, to ground at the front contact of relay 2. The energization of the left-hand winding of magnet 3 attracts botharmatures of the line-switch, thereby disconnecting the winding of the line relay 2 from theline and (bridge cut-oil) winding of the line-switch magnet 3 through spring 6 to the sleeve (release) lead of the trunk 31;

As soon as ground 's; connected to the holding lead 13fthe starting relay 16 is energize'd in a' circuit which includes the brush 15 and the terminal-to which the holding lead v 13 is connected. Starting relay 16 closes an obvious circuit in which thewinding of lockmagnet 18 isenergized. The lock-magnet 18' V pulls the locking lever 19 out of engagement swltch to which t is connected. The trunk;

with the notchedsector of the arm 20, and closes a circuit-through sprlng 22 and its as- I soclated front contact to operate open-main relay 23.f Relay 23 disconnects battery from trunkin the group. If this trunkis idle there isno ground on the corresponding ter- 1 minal, with which brush 15 is nowin contact, and relay 16, releases. The release of relay 16 causes the release of lock-magnet 18 so that. the lock-lever 19 engages a notch in the sector of the arm 20-to hold the line-switch plungers, which are engaged bythe shaft 14, opposite the springs ofthis idle trunk. .If this trunk were busy, the starting relay 16 and lock-magnet 18 would beheld operated and the shaft would continue to rotate until the l brush 15,1na-de contact with the terminal of an idle trunk. When the shaft 14 reaches the'position corresponding to the last trunk, the arm 2O closesthe contacts 24:. If this last trunk is busy,relay 16 and magnet 18 do not release and trip relay 25 is operated. Relay 25, which is locked in its operated position by the latch 28, connects ground to lead 17 to hold the lock-magnet 18 0perated and closes an obviouscircuit for energizing the solenoid 26. The solenoid draws in its plunger 27 thereby forcing the arm 20 and shaftll back to the position in which the en gaged line-switch plungers are opposite the first trunk, trunk-31. While moving back been released by the restoration of the/1'6".

to this position the shaft 14 picks up (re-engages) all disengaged plungers which have ceiver to the receiver hook at the associated calling station. When the ar1n20 reaches the position corresponding to trunk 31, the latch 28 is moved to releaselthe armature-t trip relay25. The release oi the armature of trip relay 25 releases lock-magnet 18 unless starting relay 16 is held operated bya ground on the holding lead 18 of trunk 31.

Lead 62, which connects the'winding of relay 29 in the primary'master-switchyE to *the secondary mastenswitch H- is multipled j to all other primary master-switches which are associated with primary line-switches having access to trunks terminating at secondary line-switches in the group with which themaster-switch H isassociated. lVhenever all of the trunks to which a'secondary line-switch has access are busy (for instance,-

when'ever all of the trunks to which the switches F and G have access), the asso-:

ciated master-switch is effective, to connect ground to lead 62, and thereby operate relay 2 9 of master-switch E and the corresponding. relay in all of the JIIQLStQr-SWltGhBS to which lea-ch32 is multipled. Each of these master-switches then functions to pick upall disengaged line-switch plungers and to set themopposite the first idle trunk in each of the groups to whichthe groups of lineswitches have access. The trunking scheme being as hereinbefore described-this pick-up 7 action of the primary masterswitches results, as far as possible, in the presel'ection of trunks to d1iierentsecondary groups in whlch one or more of the trunks to which the vsecondary line-switches have access are idle. In master-switch E, the grounding of lead 62 operates relay 29. Relay 29 connects ground to lead 17 to operate trip magnet 18, and closes a'locking circuit to ground through the hack contact of relay 25. The operation of trip magnetlSreleases the arm 20 which swings to its end'position in which spring 2 1 is actuated to operate relay Relay 25 locks and the operation ofso'lenoid 26 swings the shaft ldback tothe position opposite the first trunk. Relay 29 releas'eswhen relay 25 operates. Further operation oithe masterswitch E is similar to that describedin the preceding paragraph.

hen the plunger 9 moved into the bankbetween'the springs 4: and6, as hereinbefore described, a circuit was closed from battery through the front contact of relay 58in the secondary inastei switch H, through the right-hand winding of relay 59, armature and back Contact ofrelay 59, open-main battery lead 51, winding of line relay 32 of the secondary line-switch F, normally closed contacts and left-hand (pull-down)winding of the line-switch magnet 33, over the holdmg lead 13 of trunk 81, to the ground on" spring 7 of the line-switch D. 1 Lead 51 is niultipled, as shown, to the winding of relay,

42 of secondary line-switch Grand to the windings'of similar relayslin each of the other switches inthe group with switches and G. Relay 32 andiline-switch magnet33 oper-- ate, in the circuit to ground overthe holding lead of trunk 31, but relay 59 is marginal anddoes not operate unless ground is simultaneouslyconnected bythe operation of pri-- mary line-swi-tches to the holding leadsof two or more trunks which terminate at secondary lineswitches in the group with which the open-main battery lead 51 .is associated.

Such a condition will be'considered later in.

this. description. 7 When relay 32 of secondary switch F operates, a circuit is'closed from battery through the right-hand windinglof the magnet 3 of lineiswitch D, spring 6 and. associated front the armature "8 in its operated position although not sufficient to. attract this tarmature :fromits normal position; the left-hand (bridge cut-oft) armatures of magnet 3. are

also held in their opera-ted position; Line relay 20f switchD is. slow to release so that theline-switch magnet :3 is held energized by relay2, after relay 2 is disconnected from the line 1% hereinbefore described, long by the operation of relay .32., The ground which was'connected to the release lead of trunk 31,ashereinbefore described, to ener gize the right-hand winding of the magnet 3,is also effective as a busy potential to pre- Vents'eiZure of theline ,1 by any of the connectors to whose banks the line is multipled.

Assume that the'shaft 54 of the secondary master-switch H 'is in' the position in which the engaged secondary switch plungers,'includingthe pl'ungerot switch F, are opposite the springsoftrnnk 68. The energizationof the left-hand winding of magnet 33, as herein 7 before described, is effective to attract the right-hand (pull-down) armature 38 and thus thrust the plunger 39 into the bank between springs 34 and 36; thetip, ring and release leads of trunk 31 are thereby extended through springs 34,35 and 86 of secondary switch F to the tip, ring and release leads of trunk '63. The energization of magnet 83 is also effective to attract its left-hand armature, thereby disconnecting the branch from the open-main batterylea'd 51 through therwinding' of relay 32 from the holding lead of trunk 31, and closing a locking circuit from battery throughthe right-hand winding of magnet 33, armature and front 100 enough for the circuit through the'right hand winding ofniagnet 3-to have been'established' contact offmagnet-33, left hand winding of magnet .33, over the holding lead of trunk 31, to ground at spring 7 of primary switch D.

The movement of plunger 39 of secondary line-switch F, as her'einbefo-re described, also,

v closes a circuit from ground-through spring 37 and the associated front contact of switch- F, through lead 52 andthe 't er'minal'to which it connects, brush .55 of-the master-switch H,

and-through the winding of starting relay 56: to battery...-Relay 56operates inth1s circuit:

connectingrg'round over lead; 57'to the lock magnet (not-shown) of. master-switch; H.

. 54 is being moved.

The shaft of master-switch H is thus re;

leased and moves to a position; opposite the.

next trunk, in a similar manner to that 1n which the shaft. ,of master-switch 'E 'was' moved when trunk 31" wasiseiz'ed. by the primary' line-switch D, I as hereinbefore described. Theoperationof starting-relay 5.6 also opens the circuitforlfthe normally 'operatedopengniain relay 58. Relay58; releases, thereby. disconnecting batteryv from the open-main battery lead .51 so that none (not shown) .of selector S are effective to con-.

nect ground to the release lead oftfunk63 so as to holdtheright-ha'ndwinding of magnet 3 ofprimary line-switch D energized and thus I prevent release of the connectlon; Relay 32 is slow to release so that this winding of mag:

net 3 is held energized in the circuitover the;

holding lead of trunk 31 to. ground. onspring 7 of switch D until after the ground inselector S has been connectedto oftrunk 63. v The-selector S is the release lead then controlled by the actuation of the calling device at the station A to select agroup of trunks which terminateat connectorswitcheswhich have access tothe; line 68 of the called station B. The selector S automatically selects an idle trunk, iii the selected-group, whichis represented by the trunk 66 which terminatesat the connector C. Thefrelease lead of trunk63 is extended through the sleeve brush of selectors to the r a. releaselead of trunk 66. Ground is connectedin-the usual-manner at the connector G-to the release lead of trunk 66 to hold the magnet 3 of primary. line-switch D energized, untll the connection is released by replacing the re. ceiver on the recelver hook at the callingsta.

tion A. -The ground at selector S is removed from the release lead as soon as sufiicienjt time has elapsed for ground to have been connected to the release lead; oftrunk 66 by the connec-v tort). The connector!) is controlled by the called. subscriberanswers, the talking conned tion is established between stations A andB. When the connection is released by replacing the receiver'on the hook at the calling station A, the. ground at connector 7 is disconnected from the release lead of .trunk66 thereby releasing magnet 3 of primary lineswitch D, The consequent release of arma-' ture .8 withdraws the-plunger 9, disconnecting. the line 1 from the trunk 31; and the releaseofthe left-hand armatures of magnet 3 connects the winding of line relay 2 to the line l-in-readiness for theorigination of another call; a

- Now assume that, the trunk 41is'seizedby a primary line-switch having access thereto at the same time that trunk 31 is seized bythe primary line-switch D.,- In this case the branch from open-main battery lead 51 through the winding of relay 32, left-hand winding of 1nagnet 33, over the holding lead of trunk 31to ground at spring 70f switch D, is paralleledby the branch from, lead 51 through thewinding. ofrelay 42, left-hand winding of magnet 43, over the holding lead of trunk 41 to ground at the corresponding spring of thepriinary line switch which has seized trunk'41.- The closing of these two: branches-is effective to operate marginal re-. lay 59 before the slower actingline-switch magnets 33 and 43 a're operated. Relay 59 locks through its left-hand winding and front contact in series with the winding of relay 60 to ground atthefrontjcontact of relay 61. Relay '59 also opensi the open-main battery lead 51 to prevent the operation of the magnets 33 and 43, and to release relays32 and 42' if already operated; it also connects ground to fpick-up' lead 62 to cause a redistribution: (as hereinbefore described) of the primary line-switches having access to trunkstermlnating at secondary line-switches in} the group withswitches F and G; -With relays 32 and42 in theirnormal position there is no circuit for [energizing the right-hand winding magnet 3 of primaryline-switch D, nor for energizing the corresponding winding of the magnet of the primary line-switch which seized trunk 41. As a result these primary switches are released and their disengaged plungers are re-engaged by the shafts of the associated master-switches and are positioned opposite trunks to diiferentsecondary groups. Relay 60, when energizedin the circuit described for holding relay 59, releases the normally operated relay 61. The release of relay 61 releases relays 59 and 60. Relays 60 and 61 areslow to .release to insure the re-' lease of the two or more primary line-switches main battery lead.

The arrangement shown in thedrawing is therefore eliective to prevent the simultaneous actuation of two or more secondary lineswitches. It is also effective to prevent an inrmediate recurrence of the condition by redistributing the groups oi antecedent switches with respect to the grcupsoi trunks to which these antecedent groups have access.

lVhat is claimed is:

1. Ina telephone system, calling linest'erminating in primary line-switches, secondary line-switches accessible-to said primary line- .switches, and means operative in the event a plurality of said secondary line-switches are simultaneously seized to prevent the operation of said plurality of secondary lineswitches and to cause the release of those of said primary line-switches by which said plurality of secondary line-switches .were seized. i

2. In a telephone system, subscribers lines, a group of automatic switches, means for seizing an idle one of said automatic switches in extending a connection from a calling toa called line, selector switches, each of said se lector switches being accessible to a plurality of said automatic switches, and means eii'ective upon the simultaneous seizure of plurality of said automatic switches for preventing the seizure of a selector switch by any of said plurality of automatic switches.

3. In a telephone system, a group of automatic switches, trunks accessible to the switches in said group, antecedent switches, other trunks accessible to said antecedent switches, each of said other trunks being permanently connected to a switch in said group, and means effective in the event that two or more of said other trunks are simultaneously seized for preventing the actuation of any of the automatic switches in said group to which said two or more other trunks are connected.

4. In a telephone system, groups of automatic switches, groups of trunks each trunk leading to an automatic switch in a difierent one of said groups of automatic switches, groups of antecedent switches each antecedent switch having access to one of said groups of trunks, other trunks accessible to said automatic switches, and means individual to each of said groups of automatic switches and effective upon the simultaneous seizure of a plurality of said automatic switches'for preventing the seizure of a said other trunk by any of said plurality of automatic switches. r I

5. In a telephone system, groups of trunking switches, groups of trunk lines each trunk line leading to one of said trunking switches,

selective switches each having access over the trunk lines intone of said groups of trunk 1 lines toa plurality of said groups .of trunkingsjwitches, callinglines each leadingto one o',t-"said selective switches,- and, means etl'ective. in the; event that a pluralityof trunk lines leading to switches in oneof said groups trunkingswitches are simultaneously a. zedbyxselectiveswitchestoI-prevent the 0peration of the switches towhich the said plurralityt of trunlrlines lead and to cause the releaseofthe selective switches by which said iplura-lity of trunk; lines were seized.

6. In a telephone system, calling lines terminating in automatic switches, secondary switches accessible to said automatic switches, means effective to prevent the minating in primary line-switches, second{ ary line-switches accessible'to said primary linesswitches, plunger magnetsflone for each of said secondary line-switches, a marginal relay, a source of current, means for con necting said source through a winding of said marginal relay to said plunger magnets of a group of said secondary line-switches,

and means including said marginal relay effective in the event a plurality of said secondary line-switches are simultaneously,

seized to prevent the operation of said plurality of secondary line-switches and to cause the release of those of said primary lineswitches by which the said plurality of secondary line-switches were seized.

8. In a telephone system, groups of subscribers,- lines each'line terminating in an automatic switch, groups of trunks, groups oftrunking switches, each of said automatic switches having access to the trunks in one of said groups of trunks, each of said trunks terminating in one of said trunking switches so as togive each of said groups of subscribers lines access; to a plurality of groups of said trunking switches, means individual to each of said groups of trunking switches for preventing the simultaneous operation of a pluralityof switches in the associated group i. simultaneous operation of a plurality of i i i'jsmos' "net for each offs aid switches fcr operating 7 the same to further extends calling line to .-an idle'one of. said trunks, a battery','a cond'uctoi' for connecting said battery" to the r h "windings of said relays,'a'nd a control relay having a windinginseries with" said. cn-

ductor for preventing'the operation of any "of said magnets in the event that a plurality 01 saidswitches aresimultaneously seized.

In testimony whereof, Iha've signed my name to -this specification this 31st day of May, 1929.- V

i GEORGE H. MORENOY. V

zef 

